1. Field of the Invention
The present invention relates to an organic light emitting display device and a method of driving the same.
2. Discussion of Related Art
An organic light emitting display device is a self-illuminating device and has an improved viewing angle as compared with other display devices such as a liquid crystal display device. The organic light emitting display device has a higher light-emitting ability for its power consumption in comparison to other display devices. The organic light emitting display device can be easily manufactured to have a thickness thinner than those of other display devices.
An organic light emitting display device may be categorized into an active type and a passive type depending on the driving method.
In an active organic light emitting display device, each pixel has a driving circuit. A data signal is applied to a pixel selected through a scan line. The data signal is maintained in a capacitor during a light emitting period of the pixel. Therefore, since it is unnecessary to supply the data signal to the pixel throughout the light emitting period, the driving power of the pixel can be decreased. However, in the active organic light emitting display device, each of the pixels includes a thin film transistor and a capacitor in addition to an organic light emitting diode, and therefore, its configuration is complicated.
On the other hand, in a passive organic light emitting display device, each pixel includes an organic light emitting diode, an anode electrode and a cathode electrode, so that a light-emitting operation is performed by a data voltage or current applied between the anode and cathode electrodes. That is, the passive organic light emitting display device has a configuration relatively simpler than that of the active organic light emitting display device because it is unnecessary to provide a thin film transistor to each of the pixels, and the like. Accordingly, the passive organic light emitting display device can be easily manufactured.
A passive organic light emitting display device includes a panel unit having a plurality of pixels, scan lines through which scan signals are supplied to the pixels, and data lines through which data signals are supplied to the pixels. Particularly, the scan lines are coupled to cathode electrodes of the pixels. Generally, even-numbered and odd-numbered scan lines are alternately coupled from the left and right of the panel unit.
That is, the operation of applying a scan signal to the scan lines can be alternately performed on the left side and right side of the panel unit. As an example, the odd-numbered scan lines receive a scan signal supplied from the left side of the panel unit, and the even-numbered scan lines receive a scan signal supplied from the right side of the panel unit.
However, in the passive organic light emitting display device having such a structure, when a voltage drop (IR drop) is caused by line resistance of the scan lines, a luminance difference between pixels coupled to adjacent odd-numbered and even-numbered scan lines is increased toward both the left and right ends the panel unit. Therefore, a horizontal-stripe phenomenon may occur, thereby degrading image quality.